Filter device with coupling element

ABSTRACT

The invention relates to a filter device with a filter element (1) which can be received in a filter housing that consists of at least two interconnectable housing parts (17, 19). The filter element (1) can be fixed to a housing part (19) in a removable manner by means of a screw connection (32, 33), and an additional screw connection (17, 41) is provided for connecting the housing parts (17, 19). The invention is characterized in that in order to transmit a torque between threaded elements (33) of the screw connection (32, 33) and of the additional screw connection (41), said threaded elements being rotatable relative to each other, a coupling device (43, 46, 61) is added which allows an additional rotational movement of the threaded element (17) of the additional screw connection (41) when the threaded element (33) of the screw connection (32, 33) reaches the fixed rotational state.

The invention relates to a filter device having a filter element, which can be mounted in a filter housing, which consists of at least two interconnected housing parts, wherein the filter element can be detachably attached to a housing part by means of a screw connection and a second screw connection is provided for connecting the housing parts.

Filter devices having at least one filter element, which can be mounted in a housing, through which at a certain system pressure or fluid operating pressure fluids can flow are state of the art and are widely used, for instance, in system branches of hydraulic systems through which hydraulic oil flows. A filter device of the type mentioned, in which the filter element can be connected to a housing part by means of a screw connection and the housing parts forming the housing of the device can also be connected to one another by means of a screw connection, is disclosed in the document DE 10 2011 120 680 A1. In this known filter device, the filter element has an internal thread forming a threaded element of a screw connection at the opening of an end cap, which screw connection can be used to fasten the filter element to a housing head, which forms a housing part of the overall housing consisting of the housing head and the housing body and has an external thread as a threaded element of screw connection with the filter element. The filter head can be screwed to the filter pot via a further screw connection.

The operational reliability of hydraulic systems in which such filter devices are used to filter the operating fluids used is highly dependent on the proper functioning of the filter devices. To prevent malfunctions that can result in damage to or failure of relevant hydraulic systems, careful maintenance of the filter devices is required, in particular degraded filter elements have to be replaced by new filter elements. To enable efficient operation, it is essential that the maintenance, in particular the filter element replacement, can be performed quickly and safely. The known filter devices leave quite a bit to be desired in this respect. Even though the mentioned, known filter device is characterized by a favorable operating behavior insofar as the filter element is securely fixed in the filter housing by a screw connection, the maintenance is relatively time consuming, because for assembly and disassembly of the filter elements in question, in each case two screw connections have to manipulated independently. For mounting “fresh filter elements”, the screw connection on the filter head removed from the housing body has to be tightened; thereafter the screw connection of the filter head to the filter pot is made. Correspondingly, two separate steps in the workflow are required for disassembly.

Based on this prior art, the invention addresses the problem of providing a filter device of the type mentioned at the outset, which is characterized by an improved ease of maintenance.

According to the invention, this object is achieved by a filter device having the features of claim 1 in its entirety.

According to the characterizing part of claim 1, one essential feature of the invention is that a coupling device is inserted for transmitting a torque between threaded elements, rotatable in relation to one another, of the one and the other screw connection, which coupling device permits a further rotational movement of a threaded element of the other screw connection upon reaching the tightened state of a threaded element of the one screw connection. In this way, both screw connections can be actuated in a single operation, in which only one of the threaded elements is rotated by the maintenance person, i.e. by means of a rotary actuation both the tightened state between the filter element and the associated housing part and the tightened state of the housing parts among each other are attained, thereby significantly reducing the time required for maintenance.

The arrangement can advantageously be made in such a manner that the filter housing has a housing body, to which the threaded element of the first screw connection having a filter element can be attached by means of this screw connection, and a housing head, having a threaded element of the second screw connection, which housing head can be connected to the housing body by means of the second screw connection, as housing parts.

In particularly advantageous exemplary embodiments, the coupling device comprises two coupling parts, of which one coupling part is mounted in the housing head secured against rotation, and the other coupling part is part of an end cap of the filter element, which end cap can be attached to the housing body, and that the one coupling part mounted in the housing head is movable in the axial direction of the screw connections. In this arrangement the housing head associated to the coupling part forms the drive-end coupling part for actuating the second screw connection between the filter element and the housing body during the rotational movement of the housing body, which the operator performs for screwing the housing body and the housing head, wherein the coupling engagement with the coupling element located on the filter element is maintained during screwing because of the axial mobility of the one coupling part.

With particular advantage, the one coupling part allocated to the housing body may be formed as an annular driver element having at least one projecting driver cam, which has at its free end region a contact chamfer on one side and a limit stop on its other, opposite side.

In that case, the end cap may have, as part of the other coupling part, on its free front face at least one coupling wedge having on its one side a guide chamfer and on its other, opposite, side an abutment surface. In this design of the coupling device, it forms a kind of ratchet coupling, which transmits the torque exerted on the housing head by screwing due to the contact chamfer pushing the driving cams at the guide surfaces of the coupling wedges of the end cap on the latter, until the screw connection between the filter element and the housing body reaches the tightened state, whereupon the contact chamfer of the driving cams runs over the guide chamfer of the coupling wedges at the end cap, resulting in the housing head remaining rotatable until the tightened state of screwing the head on the housing body has been reached. For a disassembly conducted after the assembly, the coupling device acts as a rigid coupling, the rotational movement being performed in the opposite direction of rotation, wherein the limit stops of the driver cams rest against the abutment surface of the coupling wedges after having overrun the latter. The coupling device thus forms a kind of ratchet coupling between the drive-end coupling part (drive element) and the output side coupling part (coupling wedge at the end cap).

To adjust the strength of the torque transmitted by the coupling device before the contact chamfer of the driver cams overruns the guide chamfer of the relevant coupling wedge, the annular driver element can be guided in a longitudinally displaceable manner under the action of an energy storage means, in particular in the form of a compression spring, in a receiving space of a housing part, such as the housing head, and can be held captive by a retaining device in the one housing part, such as the housing head. As a result of the spring stiffness of the pressure spring, the transmittable torque can be adjusted such that an excessive tightening of the screw connection at the filter element and any possible resulting damage to the associated sealing device are prevented. The torque can also be changed by the angle of the inclined planes of the contact chamfer and the guide chamfer. During the further rotational movement of the housing head in the course of the assembly process, the process of leap-frogging over the coupling parts continues until the screw connection connected to the drive-end coupling part and the connection of the housing body to the housing head have been tightened. In the process of dismantling where the direction of rotation is reversed, the coupling device acts as a torque-tight coupling as the contact chamfer of the driver cams rest against the abutment surface of the coupling wedges.

Advantageously, the relevant driver cam can have a snap tab on its side facing the center of the annular driver element, which can be used to latch the end cap to the driver element in forming a releasable clip connection. Assembly and disassembly are particularly convenient because the filter element, latched to the housing head, can be inserted into and removed from the housing body together with the latter.

With respect to the retaining device, which is used to hold the driver element captive in the housing head, the retaining device may have a retaining hook preferably arranged on the relevant driver cam, which protrudes outwards facing away from the center of the ring and which comes into contact with a retaining ring stationarily fixed in the housing head as soon as the driver element has reached its lowermost travel position under the action of the energy storage means.

In order to form a non-rotating axial guide for the driver element, the outwardly projecting retaining hook of the driver element can be guided in a longitudinally displaceable and non-rotating manner in a recess in the housing head or a component thereof.

In advantageous embodiments, three driver cams are arranged on the driver element and on the end cap three coupling wedges are arranged diametrically opposite of the longitudinal axis of the filter element.

With respect to the formation of the screw connection connected to the coupling part at the output side, the arrangement may be such that during a rotational movement of the one housing part relative to the other, in particular when the housing head is screwed to the housing body, the coupling device drives the filter element such that its other free end can be screwed to a threaded connector of the other housing part, such as the housing body.

In order to ensure that the screw connection connected to the coupling part at the output side is tightened before the screw connection connected to the coupling part at the drive end has reached its tightened state, the threaded elements used may differ in their pitch and/or the number of turns such that the filter element is already fastened to the threaded connector of the housing body, before the housing head has been completely screwed on.

This design of the threaded elements ensures that during screwing on, the contact chamfers of the relevant coupling wedge between the already tightened filter element and the complete screwing on of the housing head, on one end cap for a slipping coupling can run over each other and in the other direction of rotation during unscrewing may come into contact with the abutment surface of the relevant coupling wedge of the one end cap of the filter element for an engaged coupling device via the limit stop of the relevant driver cam.

Below the invention is explained in detail using an exemplary embodiment shown in the drawing.

In the drawings:

FIGS. 1 and 2 show oblique views drawn in broken lines of the upper end region and the lower end region of a filter element provided for the filter device according to the invention;

FIG. 3 shows an oblique perspective view, sectioned at an angle and drawn in broken lines, of only the bottom region of the filter housing of the exemplary embodiment of the filter device according to the invention, without inserted filter element;

FIG. 4 shows a view similar to FIG. 3, wherein the filter element shown in FIGS. 1 and 2 is located in the filter housing in the operational position;

FIG. 5 shows a longitudinal section drawn in broken lines of the upper end region of the closed filter housing of the exemplary embodiment with a filter element in the operational position;

FIG. 6 shows a perspective oblique view, slightly enlarged relative to FIG. 5, of an annular driver element of the coupling device of the exemplary embodiment;

FIGS. 7 and 8 show perspective oblique views drawn in broken lines, in which different positions the coupling parts of the coupling device assume in the course of the assembly process are shown, which assembly process is performed for mounting the filter element and for closing the filter housing;

FIG. 9 a representation corresponding to FIGS. 7 and 8, wherein the operating position of the coupling parts is shown during disassembly. and

FIG. 10 shows a side view, drawn on a smaller scale, of the housing head removed from the housing body of the exemplary embodiment, the filter element being secured thereto by means of a clip connection.

FIG. 1 shows only the upper end portion of a filter element 1, which is provided for use in the exemplary embodiment of the filter device according to the invention shown in the drawings. The filter element 1 formed in the manner of a replaceable filter cartridge has at its upper end, as shown in FIG. 1, an end cap 3, which forms a border for the facing end of a filter medium 5 in the manner typical for such filter elements, which preferably consists of several pleated layers and forms a hollow cylinder, which, cf. FIGS. 4 and 5, surrounds an inner filter cavity 7, in which a fluid-permeable support tube 9 is located, whose end facing the end cap 3 has been mounted in conjunction with the end of the filter medium 5 in the end cap 3. An end cap 11 is located at the lower end shown in FIG. 2, which end cap forms the enclosure for the facing end of the filter medium 5 and the support tube 9 in the same manner as the upper end cap 3. Unlike the upper end cap 3, which closes the inner filter cavity 7 at the upper end using a continuous, planar plate 13, the lower end cap 11 has a central opening 15. During the filtering process, in which the filter medium 5 can be traversed from the outside thereof towards the inner filter cavity 7, the filtered filtrate exits from the filter element 1 through the opening 15.

With respect to the housing parts of the filter housing holding the filter element 1, FIGS. 5 and 10 show a housing cover or head 17 and FIGS. 3 and 4 show the lower end portion of a housing body 19. At this housing body, a bottom part 21 forms the lower end of a cylindrical main part 23 of the housing body 19 receiving the filter element 1, the upper, open end 25 of the housing body can be closed by the removable housing head 17. It has a fluid inlet visible in FIG. 3, through which the fluid to be filtered flows during the filtering process into the space 27 between the outside of the filter medium 5 of the filter element 1 and the inner housing wall. The inlet is limited in this respect. The bottom part 21 has a discharge channel 29, which faces the inlet channel as shown in FIG. 3. for discharging the filtered fluid from the housing body 19.

The filter element 1 can be mounted in the housing body 19 of the filter housing by means of a screw connection, whose one threaded element is formed by a threaded connector 31, axially protruding into the housing main part 23, having an external thread 32, which forms the mouth of the outflow channel 29 inside the housing, cf. FIGS. 3 and 4. The filter element 1 has an internal thread 33 as second threaded element that can be screwed on the threaded connector 31. It is located on the inside of a connecting piece 35 which surrounds the opening 15 on the lower end cap 11 of the filter element 1, wherein the free end rim of the connection piece 35 forms a sealing surface 37. For a tightened screw connection, the seal is formed by pressing the sealing surface 37 on a contact surface 39 at the bottom part 21.

The housing head 17 can be attached to the housing body 19 by means of a second screw connection, which is formed by a threaded section 41 between the housing head 17 and the region of the housing main part 23 adjacent to the end 25. FIG. 5 shows the fully screwed-on state of the housing head 17. A coupling device, which transmits rotational movements of the housing head 17 to the filter element 1 during screwing or unscrewing the housing body 19 in order to tighten or loosen the screw connection formed between the filter element and the housing body 19, has coupling parts, one of which is disposed secured against rotation within the housing head 17 and the other coupling part is part of the facing upper end cap 3 of the filter element 1. The coupling part associated with the housing head 17, which coupling part forms the drive-end coupling part in the transmission of rotational movements performed for screwing or unscrewing the housing head 17, is a driver element 43 provided in the form of an annular body. It has retaining hooks 45 radially projecting from its circular outer side, which are used to guide it non-rotatably and axially displaceably in axially extending recesses 47 in the inside of the housing head 17. For the axial movement in the direction of the open end of the filter head 17, the annular driving element 43 is pre-tensioned by a compression spring 46, but is held captive against a complete escape from the housing head 17 by means of a retaining device, which is formed in the exemplary embodiment by a snap ring 49 seated inside the housing head 17, over which the curved bottom 51 of the retaining hooks 45 can extend. As can be seen most clearly from FIG. 6, the annular driver element 43 has one axially protruding driver cam 53 each at the bottom side in FIG. 6 and oriented circumferentially towards the three retaining hooks 45. Every driver cam 53 has a contact chamfer 55 on one of its circumferentially facing sides and a limit stop 57 on its other, opposite side. On the side facing the center of the annular driver element 43, each driver cam 53 also forms a latching projection 59 protruding radially inwards.

The other coupling part, which serves with respect to the rotational movements of the housing head 17 and the driver element 43 as the coupling part at the output side, as can be seen most clearly in FIG. 1, is formed by three coupling wedges 61, which are arranged on the top side of the upper end cap 3 formed by the plate 13 in an axially protruding manner. Every coupling wedge 61 has a guide chamfer 63 on one side and an abutment surface 65 on the opposite side. As FIG. 1 also clearly shows, an axially projecting cylindrical part 67 is formed in the central region of the plate 13 of the end cap 3 between the coupling wedges 61, on the free end rim of which, a rib-like, projection 69, protruding radially outward, is formed. The filter element 1 can be latched to this projection by means of latching projections 59 located at the drive cams 53 using the annular driving element 43 such that it is secured to the latter, but can be axially moved relative to the driver element 43 according to the height of the cylinder part 67.

The installation process to be performed for inserting a filter element 1 into the opened filter body 19 and to close the housing body 19 using the housing head 17 can be performed in the device according to the invention such that the filter element 1 is secured to the housing head 17 by latching it to the driver element 43 and inserting it in the housing body 19, whereupon the housing head 17 is rotated for screwing it onto the housing body 19, cf. FIG. 7, where this rotational movement is indicated by a rotary arrow 71. The driver cams 53 of the driver element 43, whose contact chamfer(s) 55 run against the guide chamfers 63 of the coupling wedges 61 under the action of the compression spring 46, transmit this rotational movement to the end cap 3 of the filter element 1, such that it is screwed onto the threaded connector 31 on the bottom part 21 using the internal thread 33 of the lower end cap 11 until this screw connection reaches the tightened state, in which the sealing surface 37 of the end cap 11 forming a sealing edge reaches the contact surface 39 of the bottom part 21 for sealing contact. Upon reaching this tightened state, in the case of further rotation of the housing head 17, the driver cams 53 run over the guide chamfers 63 on the coupling wedges 61 of the end cap 3, cf. FIG. 8, such that the coupling device, forming a spring-loaded ratchet coupling permits a further rotation of the housing head 17 for tightening the second screw connection between the housing head 17 and housing body 19. During the insertion of the filter element 1, in one single operation, the filter element 1 can be mounted by actuating the first screw connection on the threaded connector 31 in the housing body 19 and the filter housing can be closed by attaching the housing head 17. During disassembly and the resulting opposite rotational movement of the housing head 17, the coupling device, as shown in FIG. 9, acts as a rigid coupling, wherein the limit stops 57 resting against the abutment surfaces 65 of the coupling wedges 61 jointly rotate the filter element 1 for loosening the screw connection with the threaded connector 31. Upon further rotational movement, the second screw connection between the housing head 17 and housing body 19 becomes detachable, such that the filter element 1 to be replaced can be removed in conjunction with the filter head 17 and the disassembly process can also be performed in one operation.

By adjusting the spring stiffness of the compression spring 46, the tightening torque of the filter element 1 achievable for the overrunning the coupling parts can be adjusted such that any damage to the sealing edge on the sealing surface 37 is avoided. In the design of the threaded elements of the two screw connections, the pitch and the number of threads are designed such that the screw connection 32, 33 between the filter element 1 and the bottom part 21 of the housing body 19 is tightened or loosened before the second screw connection 41 between the housing head 17 and the housing body 19 is tightened or loosened. For example, in the illustrated exemplary embodiment, the first screw connection at the lower end cap 11 and at the threaded connector 31 is formed as a thread having a pitch of 4 with four turns, while a fine pitch between housing head 17 and housing body 19, having a pitch of 1.5 is formed with six turns. 

1. A filter device having a filter element (1), which can be mounted in a filter housing, which consists of at least two interconnected housing parts (17, 19), wherein the filter element (1) can be detachably attached to a housing part (19) by means of a screw connection (32, 33) and a second screw connection (17, 41) is provided for connecting the housing parts, characterized in that a coupling device (43, 46, 61) is inserted for transmitting a torque between threaded elements (33), rotatable in relation to one another, of the one and the other screw connection (32, 33), which coupling device permits a further rotational movement of a threaded element (17) of the other screw connection (41) upon reaching the tightened state of a threaded element of the one screw connection.
 2. The filter device according to claim 1, characterized in that the filter housing has a housing body (19), to which the threaded element (33) of the first screw connection (32, 33) having a filter element (1) can be attached by means of this screw connection (32, 33), and a housing head (17), having a threaded element (41) of the second screw connection, which housing head can be connected to the housing body (19) by means of the second screw connection (41), as housing parts.
 3. The filter device according to claim 1, characterized in that the coupling device comprises two coupling parts (43, 61), of which one coupling part (43) is mounted in the housing head (17) secured against rotation, and the other coupling part (61) is part of an end cap (3) of the filter element (1), which can be attached to the housing head (17), and that the one coupling part (43) mounted in the housing head (17) is movable in the axial direction of the screw connections (32, 33; 41).
 4. The filter device according to claim 1, characterized in that the one coupling part may be formed as an annular driver element (43) having at least one projecting driver cam (53), which has at its free end region a contact chamfer (55) on one side and a limit stop (57) on its other, opposite side.
 5. The filter device according to claim 1, characterized in that the end cap (3) has, as part of the other coupling part, on its free front face at least one coupling wedge (61) having on its one side a guide chamfer (63) and on its other, opposite, side an abutment surface (65).
 6. The filter device according to claim 1, characterized in that the annular driver element (43) is guided in a longitudinally displaceable manner under the action of an energy storage means, in particular in the form of a compression spring (46), in a receiving space of a housing head (17) and is held captive in the housing head (17) by a retaining device (45, 59). (Currently amended) The filter device according to claim 1, characterized in that the relevant driver cam (53) has a snap tab (59) on its side facing the center of the annular driver element(43), which can be used to latch the end cap (3) to the driver element (43) in forming a releasable clip connection.
 8. The filter device according to claim 1, characterized in that the retaining device has at least one retaining hook (45) arranged on the annular driver element (43), which protrudes outwards facing away from the center of the ring and which comes into contact with a retaining ring (49) stationarily fixed in the housing head (17) as soon as the driver element (43) has reached its lowermost travel position under the action of the energy storage means (46).
 9. The filter device according to claim 1, characterized in that the outwardly projecting retaining hook (45) of the driver element (43) can be guided in a longitudinally displaceable and non-rotating manner in a recess (47) in the housing head (17) or a component thereof.
 10. The filter device according to claim 1, characterized in that the three driver cams (53) are arranged on the driver element (43) and on the end cap (3) three coupling wedges (61) are arranged diametrically opposite of the longitudinal axis of the filter element (1).
 11. The filter device according to claim 1, characterized in that during a rotational movement of the one housing part relative to the other, in particular when the housing head (17) is screwed to the housing body (19), the coupling device (43, 46; 61) drives the filter element (1) such that its other free end can be screwed to a threaded connector (31) of the housing body (19).
 12. The filter device according to claim 1, characterized in that the threaded elements (32, 33, 41) used may differ in their pitch and/or the number of turns such that the filter element (1) is already fastened to the threaded connector (31) of the housing body (19), before the housing head (17) has been completely screwed on.
 13. The filter device according to claim 1, characterized in that during screwing on, the contact chamfer (55) of the relevant driver cam (53) and the guide chamfer (63) of the relevant coupling wedge (61) between the already tightened filter element (1) and the complete screwing on of the housing head (17), on the one end cap 83) can be run over in the case of a slipping coupling and in the other direction of rotation during unscrewing may come into contact with the abutment surface (65) of the relevant coupling wedge (61) of the one end cap (3) of the filter element (1) for an engaged coupling device (43, 46; 61) via the limit stop (57) of the relevant driver cam (53). 